Analytical expressions have been derived for the thermoelastic stresses in a threelayered composite beam system having a middle layer of functionally graded material (FGM). Continuous gradation of volume fraction in the FGM layer is taken in the form of the mth power of the coordinate axes in the thickness direction of the beam. Using a single algorithm, solutions for the beams with continuous gradation in the FGM layer of linear, quadratic, or cubic nature, can be obtained just by changing the value of ‘ m’. A numerical scheme of discretizing the continuous FGM layer (in sublayers) and treating the beam as a discretely graded structure has also been discussed. Appropriate expressions for the solution have been derived for the power law gradation (mth power) of the FGM layer. A discretized FGM layer scheme has been shown to give results practically matching with the results obtained analytically.